Summary of the invention
The purpose of this invention is to provide a kind of method that adopts the image invention to carry out the judgement of laser cleaning effect, the method will be converted to the calculating of laser cleaning area the statistics of image pixel number, utilize corrosion layer and material surface to become the different realization with brightness range of the average automatic decision of image lower of white light.
Technical scheme of the present invention is: a kind of method of automatic decision laser cleaning effect may further comprise the steps:
1) shines unattacked metal material surface with white light source, obtain the basic coloured image of described unattacked metal material surface, calculate the RGB average of basic coloured image
Described basic coloured image is converted to basic gray level image, calculates the gray threshold of described basic gray level image
2) with the sample surfaces after the white light source irradiation cleaning, obtain the coloured image of sample surfaces, the coloured image that obtains is carried out pre-service, calculate the RGB average of described coloured image
3) the RGB average of the RGB average of comparison step 2 described coloured images and the described basic coloured image of step 1), when
In time, is judged as totally and cleans up.
4) with step 2) described coloured image is converted to gray level image, with the gray scale of each pixel of gray level image
With gray threshold
Compare, when
In time, is judged as this pixel and cleans up.
5) ratio of the pixel count n that cleans up described in the described step 4) of calculating and the total pixel number N of gray level image is cleaning efficiency
Gray threshold in the described step 1)
Average gray value for described basic gray level image.
Beneficial effect of the present invention: utilize reflected light image color and the monochrome information of different material under the white light to have different characteristics, to be converted to the calculating of area pixel calculates, finish the purpose of automatic decision cleaning performance, help the robotization of laser cleaning equipment, also be convenient to integrate with other equipment, save manpower and time, and computing method are simple, computing velocity is fast, accuracy is high.
Embodiment
The method of automatic decision laser cleaning effect mainly utilizes material different, under the white light source irradiation, the different methods that detect with illuminance information of catoptrical color, whether failed, employing is calculated area and is converted to gray level image pixels statistics judgement cleaning efficiency if adopting the judgement of three primary colours average value processing to clean.
A kind of device of automatic decision laser cleaning effect such as Fig. 2, comprise laser instrument 1, optical system 2, controller 3, computing machine 7, colour plane battle array CCD8 and white light source 9, described laser instrument 1 and optical system 2 are by controller 3 controls, and optical system 2 converges to the cleaning area 5 that is cleaned material 6 surfaces with laser instrument 1 Output of laser 4 collimations.The same cleaning area 5 of white light source 9 irradiations, reflected light is received by colour plane battle array CCD8, and computing machine 7 calculates its cleaning performance.
A kind of method flow diagram of automatic decision laser cleaning effect such as Fig. 1.Before carrying out automatic decision, need to obtain first the three primary colours average of unattacked metal material surface image
With the gray level image threshold value
Because what the metal material surface that cleans up presented is the metal true qualities, and brightness is even, therefore adopts white light source irradiation metal material clean surface, and colored area array CCD is taken surface image, carry out the RGB(RGB) the three primary colours analysis, computed image RGB average threshold value
, this threshold value is close to the rgb value of metal color.Again coloured image is converted to gray level image, the gray-scale value of all pixels is added and, again divided by pixel count, and get final product
, this threshold value also is close to a constant.
Utilize the sample area after the white light source irradiation is cleaned after cleaning is finished, colored area array CCD is taken the surface image after cleaning, the image that the method pre-service of adopting contrast to strengthen gathers.Carry out equally the RGB(RGB) the three primary colours analysis, computed image RGB average
The first situation, when metal material covers corrosion layer, this moment the RGB average
Close to the rgb value of corrosion layer color, because rough surface, the light major part is scattered, and presents the shadow region, at this moment the RGB average
Might close to
The second situation, after material was cleaned totally, what present was the gloss of metal self, and owing to reflectivity improves greatly, brightness also improves much than before cleaning, so RGB average at this time
Approach or be a bit larger tham the rgb value of metal color; The third situation, when overclean, surfacing generation qualitative change, what material presented no longer is the metal intrinsic colour also, should be the color of its product, RGB average at this time
Rgb value close to the product color that is to say, can judge whether to clean up by colouring information.So with RGB average and average threshold ratio, when
The time, explanation cleans up, otherwise expression is cleaned unsuccessfully.The coloured image that cleans up is converted to gray level image, and the total element of pixel is N, represents the number of pixels that cleans up with n.Each pixel with gray level image
One by one with gray threshold
Compare, when
, explanation cleans up, and the n value adds 1, final cleaning efficiency
When cleaning efficiency reaches a certain numerical value, meet cleaning requirement.
Embodiment
At first with the clean hull steel iron surface of white light source irradiation, obtain surface image, the contrast of regulating image is 100%, tries to achieve image RGB three primary colours average threshold value [248,245,249] and gray threshold 232.
Adopt the 100W fiber pulse laser of 1064nm, pulse repetition rate is 100kHz, Duplication is 50%, and the collimation focusing optical system directly adopts the condenser lens of scanning galvanometer and 254nm, uses 10W, 50W, the laser energy of 100W cleans respectively the hull steel iron surface, and visual result is that the laser action of 10W does not clean up, and the laser of 50W cleans up substantially, the laser of 100W excessively cleans, and Fig. 3 is the exterior view of 50W laser cleaning material.After gathering image respectively, the contrast of at first regulating image is 100%, and store image information is tried to achieve respectively image RGB three primary colours average, and the image average that calculates rusty stain is [123,45,20], illustrates that the rusty stain color is for red; The laser action image of 10W is [38,35,30], and key diagram looks like not clean up near black; The laser action image of 50W is [207,214,204], and the key diagram picture approaches white, substantially cleans up; The laser action image of 100W is [103,113,91], and the key diagram picture approaches yellow, excessively cleans.Relatively compare greater than scope with average threshold value [248,245,249], only have the laser action image of 50W to meet the requirements, directly be converted to gray level image, luminance threshold is 232, compares one by one, cleaning up number is 45527, and total pixel is 61740, so cleaning efficiency is 72.74%.